Wellington Airport's proposed new air traffic control tower has been delayed, while the preferred site among the cars at Lyall Bay shopping centre undergoes geological testing.
The airport owns the land at the Lyall Bay Warehouse shopping complex but the tower would be owned and operated by Airways NZ, the state-owned company that oversees traffic control in national airspace.
Construction of the state-of-the-art navigation facility - to replace the weatherbeaten 57-year-old-tower in Rongotai - was expected to begin at the end of last year.
Airways chief executive Ed Sims yesterday blamed the delay on site investigations to ensure the new tower was seismically strong and in the best possible location.
"We wanted to make sure it was the safest location which gave us the broadest visibility, not just of the current runway but if it's widened and extended . . . but operationally I think we are convinced that is the best place for it."
The Warehouse car park sits on reclaimed land which presents its own challenges.
"You have to go deeper with the foundations and put in more strengthening work which comes at a cost.
"If it turns out that we simply cannot put the depth of foundations on that site to make that tower one of the strongest buildings in Wellington . . . then that would be a fundamental reason why we couldn't base it there."
Sims was still to be informed by contractors just how deep the tower's foundations would need to be before the cost of the "multi-million dollar" project could be calculated.
Airways NZ's traffic control operations are totally funded through its customer airlines such as Air New Zealand and Qantas.
"So ultimately it's the customer [airline passenger] . . . that pays for the tower," Sims said.
A decision on the tower is expected by the end of the year.
The existing tower's suburban Rongotai hillside location is unique among New Zealand's 17 air traffic control towers in having its own street address.
It was suggested a year ago that once the tower had been replaced it could be transformed into a public viewing platform or tourist attraction.
An Airways spokeswoman said the ideas had not been progressed.